Dyeing process



Patented June 4, 1929.

UNITEDVSITIAT'ES PATENT OFFICE.-

.AUGUSTE ESCAICH ANID JEAN PAUL WORMS, OF PARIS, FRANCE. 7

DYEING PROCESS. I

No Drawing. .Application filed November 20, 1923, Serial Illa 675,861, and'in Germany November 25,-l9 22.

A dyeing process utilizing nitrous acid in the presence of metallic salts has already been proposed, but practice has shown that this process was not practical, because the bathmust be strongly heated and for a long time with the products to be dyed and in the presence of a large quantity of mineral acids-because only brown colors are produced, and because the treated fibres are thus 10 seriously deteriorated or destroyed; this process is unusable for the treatment of leathers and furs.

The present invention has for its object a dyeing process utilizing nascent nitrous acid in the presence of metallic compounds which Y are soluble orrendered soluble, this process being applicable to all animal fibres, leathers and :t'urs at ambient temperature as in the hot state at a temperature below the boiling point.

In this process, the action of nascent nitrous acid resulting from the decomposition ofdifferent bodies containing nitrogen, for example and in the most cases, ofnitrite, in the presence of any kind of acid capable of decomposing the same' has for a result to: 1. Produce autogenous colors on fibres. 2. For increasing the available shades:

(a) of diazotizable colors developed on fibres in the known conditions at or below the temperature of the melting ice.

(blot basic colorants utilizing the tannins as morda'nts.

According to the invention i 1. Animal substances are dyed by hot treatment or by cold treatment in several hours in more or less acid baths containing alkaline nitrites' and metallic salts or oxides, both of which latter substances can moreover be in- The nitrous acid can also act in the gaseous state, by one of the usual methods of gaseous production (decomposition by water of the corporated with the fibre as mordants. All the acids capable of liberating the nitrous acid from the nitrites can be employed whether nitrosyl sulphate, reduction of nitric acid by starch or arsenious acid, etc.)

These principles are applicable not only to dyeing proper but also to vapour tinting and printing.

' 1st Emample. 20 litrcs'of water 10 to 40 grins. sodium nitrite to purple on a kilo- -l- 10 to 404:.rms. copper sulphate gram of slik or soaking about 24 hours cold or very of wool immersed quickly by heating, without it befrom the coming necessary to cause to boil mencement of the treatment.

lf to the same bathare added 50 to 200 grms. of acetic acid at 10 B. or the equiva give from old rose lent acid, the tints are more pronounced, this 1 first example proving that the metallic salts can act without any adju'vzant.

In the above example in which the metallic compound is copper sulphate, the obtained color is rosy or purple. Other metallic-substances will dye the fibres in the same condical equation:

fAlso the proportions of metallic saltsis not fixed and will vary with the desired tints.

All the metallic salts will give results while using very small amounts (0.50 grin. per litre of bath if necessary) which allows of employing expensive products such as uranium or salts. T

In the 'said specification. and claims, the term soluble is taken in a general sense and not, in therestricted sense as is often the case when the only considered solvent is water.

The multiplicationof the tints is in relations with that of the metallic salts. If each of these does not develop a. colour in itself, it

must nevertheless be remembered that variable yellows be derived from alkaline alums, from corrosive sublimate from inolybdates, tungstates, manganese salts, potassium ferri-v cyanide, and the like; reds from nickel, copper salts etc. and greens from cobalt salts etc.

The whole of the metallic salts is thus availablle whatever may be the acid generating the sa t.

The metallic oxides fixed on'fibres as mordants give similar results.

The present process can be carried out in different Ways'either by using different mixtures offibres or by varying the metallic compounds and their proportion in the dyeing bath; also, when varying the proportions of metallic compounds, it will be possible to' vary the shades either by applying the above described process to fibres which have already been dyed by known processesby means of diazo colors which require the use of ice, or by using, in order to decompose the employed I nitrite, different acids or their equivalents, whereof the quality and quantity can also be varied.

lVhat we claim is y 1. A process for dyeing on animal fibres,

consisting in causing to act upon the said fibres at a temperature ranging from the ordinary air temperature to the boiling point of water, of a soluble metallic compound in the presence of nascent nitrous acid.

2. A process for dyeing on animal fibres, consisting in causing the action uponthe said fibres at a) temperature comprisedbetween the ordinary air temperature and the boiling point of water, a soluble metallic compound in the presence of an alkali metal nitrite, and

of any acid by which nascent nitrous acid is 

